“It has previously been cited as being a symbol of all that is wrong with the high-fat, high-sugar Scottish diet.

“Whilst the reputation of the snack outwith Scotland is sometimes dismissed as an urban myth, research suggested that approximately 22 per cent of chip shops served the foodstuff.”

Robert Brown, co-chair of the McCarrison Society, who champion healthy eating, said: “The message is that if you are going to eat a Mars bar, don’t batter it first.

“The fat, the frying, the carbohydrates, the heavily processed food, all chucked in together has to be bad.

“I don’t believe we can ban deep-fried Mars bars and the like but re-education is the key.”

The infamous snack was invented at the Carron Fish Bar in Stonehaven, Aberdeenshire, in 1992.

Current owner Lorraine Watson says she still sells up to 150 a week.

She added: “It’s mainly tourists that buy them but if a child was in every day buying one, we’d be letting the parents know.

“It’s important that everything is done in moderation.”

Deep-fried Mars bars are now widely available in fast food shops across Scotland and even in some restaurants across the world.

One of Scotland's leading chip shop owners says he's never advertised the snack - but gets regular requests from tourists.

Angelo Varese, who runs the Blue Lagoon chippie chain, said: "We've never had deep fried Mars bars on our menus yet we get a lot of requests for them.

"It's mainly tourists who ask for them, rather than locals. In particular, we see a lot of Chinese tourists who ask for it. It seems like they've heard about it and want to see what it's like - it's almost like the myth has become reality."

Angelo, 54, who has 12 shops and is about to open a 13th in Ayr, said: "We'll usually try and make one for customers, as long as they supply the Mars Bar."

His son Alessandro, 22, fryer at the family's chippie in Gordon Street, Glasgow, said: "We get maybe half a dozen requests on a typical Saturday in here.

"We charge £2 to batter and fry each one. We don't actually stock Mars bars so people have to bring in their own.